Abstract: Pongamia pinnata (L.) Pierre (Fabacae) has been used in traditional medicine for treatment of diabetes. The aim of the research was to study the antihyperglycaemic activity of cycloart-23-ene-3β, 25-diol (code name compound B2) isolated by column chromatography method from stem bark of Pongamia pinnata in alloxan induced diabetic mice. The structure of compound B2 was elucidated by spectroscopical data. Diabetes was induced in mice by alloxan (80 mg kg-1, i.v.). Compound B2 was administered orally. Serum glucose level was determined at 0, 2, 4, 6 and 24 h. The onset was at 2nd h; peak effect at 6th h and the antihyperglycaemic effect was sustained until 24th h. Results obtained in the present study indicated antihyperglycaemic activity of cycloart-23-ene-3β,25-diol (B2).